Preheat oven to 425°.
Place fish in an 11 x 7-inch baking dish coated with cooking spray. Combine lime juice, mayonnaise, onion powder, and pepper in a small bowl, and spread over fish. Sprinkle with breadcrumbs; drizzle with butter. Bake at 425° for 20 minutes or until fish flakes easily when tested with a fork. Sprinkle with parsley.
Notes: Haddock or cod would make good substitutes for the grouper. Adjust the baking time depending on the thickness of the fish.
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